I think a combination of oven temperature and the convection fan.
In a conventional oven heat only radiates from the oven floor. But in a convection oven the fan circulates heat throughout the oven chamber. So heat surrounds the pan in all directions. That intense heat sets the batter in contact with the metal significantly faster than heat radiating from a fixed point. The edges on the outside of the muffin set, but the unbaked center continues to rise.
When the batter in the center reaches the top of the tin cavity, the convection fan blows it out fo the cavity. That's why the batter is outside of the cavity and flopped over to one side.
Try reducing the oven temperature and turning the fan to low or off. If the oven fan cannot be adjusted, then try placing an empty sheet pan on the rack above the tins to try to redirect the air flow.